Aurora Borealis, Churchill, Canada
Photograph by Norbert Rosing
An aurora borealis glows brightly over Churchill, Canada. Auroras occur when charged particles outside the Earth's atmosphere collide with atoms in the upper atmosphere. The result: a glowing display of curtains, arcs, and bands in the sky. The phenomenon is called aurora borealis or northern lights in the Northern Hemisphere and aurora australis or southern lights in the Southern Hemisphere.